you could probably do better putting a penny in there …lol
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yeah, I think I’ll get some new mirrors (at least to replace mirror 3) to see what (if any) difference that makes!! It just dawned on me earlier to check it 
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Better mirrors is one of the best power improvements you can do.
I would check and potentially replace them all …
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yeah, let me get a set of mirrors and see what happens then? They come on different diameters. I’m assuming the basic K40 machines are 19mm/20mm?
These seem to have the best reviews
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K40s typically have 20mm mirrors.
While your at it did you look at your lens?
the lens at the bottom of the unit seems to look ok. Prob should just also replace it. It’s much smaller than the mirrors - possibly this one (12mm)
If that fits your laser head it looks good.
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mirrors ordered to start with anyway
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If I was to get the lens, is it the 2" (50.8mm) focal length? the distance from the bed to the lens?
50.8mm / 2" is the right focal length for the default most common K40 head.
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A note for future reference, my K40 did not come stock with a FL50.8mm lens it came with a FL38.1.
It took me a while and multiple ramp tests to realize.
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Ah, I’m not actually a K40 owner; I just did a search and found it commonly referenced. 
@donkjr was your nozzle set up for a 38.1 mm engraving lens, or was it a mistake? Or does it have multiple stations for different focal lengths? My cloudray C head can run with four different focal lengths because it has two stations in a tube that can install two ways that cover three focal lengths in 20mm diameter lenses, and can install a 38.1mm 18mm diameter lens at the top of the nozzle. I know that’s more options in focal lengths than the common K40 heads though. I didn’t realize there were multiple possibilities.
Sorry to have rushed into being potentially misleading!
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The problem with K40’s as I see it is that they are made my multiple companies, who are treating it like a commodity item, sourcing the cheapest available parts they can from multiple vendors. There is no consistency even within batches of the same manufacturer. I have seen lenses from 2.5" to 1.5" installed in K40’s, Si mirrors or MO mirrors, various LPSU’s etc.
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yeah, I’ve learnt that it’s not an exact science but I knew that before I bought it originally. There never seems to be an EXACT fit or EXACT solution to each issue. A lot of trial and error but this forum has been AMAZING
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I am guessing it was a manufacturing “anomaly” I kept it because it cuts a little better I think and I wanted the K40 mostly for cutting. In a K40 you have to manually change lenses :(.
If memory serves me right the K40 was originally intended to engrave rubber stamps …
I wish I could get a C head to fit in my machine but never found a way to make it work.
You weren’t being misleading because the normal lens is (I would underline “is” if I could 
)
FL50.8. I just wanted to share that if things don’t seem right check the FL.
Before I knew of the ramp test I found this out by shining a light through the lens and the FL wasnt anywhere near 50mm.
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In the meantime I changed K40 initial setup and regular maintenance to note the possibility that the lens isn’t a 2" focal length, based on your experience. Доверяй, но проверяй… (Doveryai, no proveryai: Trust, but verify)
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Update - the mirrors arrived today so I installed and realigned. They were much thicker than the original so there was quite a bit of aligning but the PDF guide you guys gave me above greatly assisted with that in terms of which way to screw the mirror holder. I have included a pic of the old and new and if I said the difference was night and day then that would be an understatement… so, I tried a quick test engrave on slate on the bottom right and along the bottom of the bed and the results (no pic, sorry) were amazing and more true and more or less exactly the same. I didn’t get a lens as yet (it seemed to be fine) but the mirrors have worked a treat…
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So do you call this solved??
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I am ‘close’ to calling it solved 
I need to run off a couple of things tomorrow but def much better. Been a long drawn out process BUT I couldn’t have done it without the assistance here, and as someone above mentioned, I did overthink a lot of it. It takes patience, and advice but to anyone who is reading this OR reads it in the future, persevere…
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